Reticle OPC Using Overlapping VSB Shots
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Solution Overview
Problem
The existing methods for manufacturing reticles using variable shaped beam lithography are time-consuming and expensive due to the need for numerous non-overlapping, normal dosage shots, which complicates the creation of complex optical proximity correction features and increases the number of shots required, especially as feature sizes approach the limits of optical lithography.
Innovation Solution
Allowing overlapping VSB shots and varying dosages, with the union of shots deviating from the target pattern, to reduce the number of shots needed for pattern creation, thereby shortening the write time and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If non-overlapping normal dosage shots are used to manufacture reticles, then manufacturing precision is maintained, but productivity decreases and write time increases
Solution Approach 1:
The patent segments the pattern creation process into multiple overlapping shots with varying dosages instead of using numerous non-overlapping normal dosage shots. This segmentation allows the union of shots to deviate from the target pattern while maintaining final pattern accuracy, thereby reducing the total number of shots required and shortening write time.
Solution Approach 2:
The patent changes the dosage parameter across different shots, allowing varying dosages rather than uniform normal dosage. This parameter change enables overlapping shots to be used effectively, as the dosage variation compensates for the overlap and ensures the final pattern meets precision requirements while reducing the number of shots needed.
2Productivity
If overlapping VSB shots with varying dosages are used, then productivity increases and write time decreases, but manufacturing precision may be compromised
Solution Approach 1:
The patent incorporates feedback mechanisms where the simulated reticle pattern is compared against the target pattern, and the shot configuration is adjusted accordingly. This feedback loop ensures that even though shots overlap and dosages vary, the final pattern accuracy within predetermined tolerances is maintained while achieving productivity gains.
Solution Approach 2:
The patent performs preliminary simulation of the reticle pattern creation process to determine the optimal set of overlapping shots with varying dosages before actual manufacturing. This preliminary action allows the system to pre-calculate the shot configuration that will achieve the desired pattern accuracy, enabling subsequent production to proceed with reduced shot count and write time while maintaining precision.
3Manufacturing precision
If numerous shots are used to create complex optical proximity correction features, then manufacturing precision is improved, but device complexity increases and costs rise
Solution Approach 1:
The patent merges multiple shots into overlapping configurations with varying dosages to create complex optical proximity correction features. Instead of using numerous separate non-overlapping shots, the merging of overlapping shots with dosage variation achieves the same or better correction accuracy while reducing the total number of shots and associated device complexity and costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the shot count and write time, enabling the efficient production of reticles with fewer shots, while maintaining pattern accuracy within predetermined tolerances, even for complex curvilinear patterns.
Implementation Method 1
maskless direct write or charged particle beam lithography is a printing process in which patterns are transferred to a substrate such as a semiconductor or silicon wafer
Data Source
AI summary
A method for optical proximity correction (OPC) is disclosed, in which a set of VSB shots is determined, where the set of shots can approximately form a target reticle pattern that is an OPC-compensated version of an input pattern. The set of shots is simulated to create a simulated reticle pattern. A substrate image is calculated, based on using the simulated reticle pattern in an optical lithographic process to form the substrate image. A system for OPC is also disclosed.